1. Technical Field
The present invention relates to a printing apparatus, such as an ink jet type printer, that performs printing on a medium, for example, by discharging a liquid onto the medium transported onto a support table that supports the medium.
2. Related Art
A known example of this type of printing apparatus is a so-called hot-melt type printing apparatus (see, e.g., JP-A-11-115175) that, after depositing an ink that is an example of a liquid that is heated to melt and then solidifies onto a sheet of paper that is an example of a medium, heats the surface of the sheet of paper on which the liquid has been deposited so as to fix the ink to the sheet of paper. Such a printing apparatus has at a position above the sheet of paper a heater for fixing the ink.
It is preferable that this heater be provided as a common component part for a plurality of kinds of printing apparatuses that vary in the maximum width of paper that the apparatuses can carry out printing on, from the viewpoint of reducing the production costs of those kinds of printing apparatuses. To that end, it is conceivable to adopt a construction in which a plurality of small heaters are arranged in a direction orthogonal to a transport direction of the sheet of paper. This makes it possible to heat a sheet of paper throughout the entire width thereof even when the sheet of paper has a maximum printable paper width. Such a small heater includes a heating element (far-infrared quartz glass heater) that extends in a direction orthogonal to the transport direction and a reflector plate that concentrates far-infrared light emitted from the heating element onto the sheet of paper.
However, adjacent ones of the foregoing small heaters overlap with each other so that, for example, unheatable areas at two opposite ends of a small heater in the directions orthogonal to the transport direction are superposed over heatable areas of adjacent small heaters when viewed in the transport direction. For example, as shown in FIG. 19, heaters 200 are provided at a downstream side of a printing unit 210 that prints on a sheet of paper MR in a transport direction YR of the sheet of paper MR and are disposed in a stepwise arrangement that extends from an end to the opposite end of the sheet of paper MR in the direction orthogonal to the transport direction YR as it extends downstream in the transport direction. Alternatively, as shown in FIG. 20, heaters 200 are provided at a downstream side of a printing unit 210 in a transport direction YR and are disposed in a zigzag arrangement that zigzags along the transport direction YR and extend in a direction orthogonal to the transport direction YR.
In the related-art printing apparatuses shown in FIG. 19 and FIG. 20, since the heaters 200 disposed in the directions orthogonal to the transport direction YR vary in position along the transport direction YR, the ink on the sheet of paper MR is heated after different amounts of time following the deposition of ink on the sheet of paper MR which vary along the width directions of the sheet of paper M. Therefore, it sometimes happens that the amounts of time between when the ink is deposited on the sheet of paper MR and when the deposited ink solidifies vary. As a result, the drying of the ink on the sheet of paper MR may become uneven or the shrinkage of the sheet of paper MR due to the ink deposited thereon may occur to varying degrees and therefore lead to damage to the medium.